Explanation:

Specifies servers, users, and groups that are denied access to a specific
server port. The portnameparameter indicates the name of the port
you enabled in the Port Setup dialog box and in the Server document. An
asterisk (*) represents everyone listed in the Domino Directory. An
asterisk followed by a view name represents everyone listed in that view
of the Domino Directory. An asterisk followed by a slash (/) and a
hierarchical certifier's name represents everyone certified by that
certifier. For example:

Deny_Access_SPX = Terminations

The users in the Terminations group cannot access the SPX port.

It's counterpart Allow_Access_ allows access, however if ONE of these
two
is set, it automatically restricts the other. Which means once the Allow or
Deny are set, only those count. Deny will allow every thing else, Allow will
deny everything else.

IMPORTANT NOTE: Use the FULL CANONICAL Name for all names you specify.